What happened to iPhone push notification?

One of the features trailed by Apple last year for future inclusion in its iPhone SDK was push notification - the ability for apps (including games) to pop up messages or alerts to users, even when they weren't running.

However, as an interesting article on Macworld notes, the feature appears to have disappeared from Apple's roadmap since it was first promised at last year's WWDC show.

It suggests the feature may even have been pulled entirely, due to either technical hurdles or concern over the dangers of intrusive notifications.

Does it matter? It does to some companies. Social gaming firms, for example, are champing at the bit for iPhone to have similar notification features to Facebook, so friends can challenge each other asynchronously.

Still, with Apple staying silent on when or if push notification will be introduced, those bits will have to remain champed for the forseeable future, it seems.